No method is inerrant, whether it would be oral or written (or even digital for that matter).
It’s my understanding that tam does hear from Christ directly – given the ‘theism is true’ assumption above. Direct god to person interaction would be the most objective interaction, surely?
I’m not discounting the possibility of God speaking directly to people. And it certainly does happen. But on what basis can we judge what they say is true?
We have people coming all the time on this forum claiming to hear directly from God. Yet, on this forum, it has no place as evidence. It is subjective evidence in that it is based on one person’s experience. It is not something we can judge if it’s true or false. He or she could have heard from God, or just made it all up, or heard from whatever. People like to say here, “Show me the peer reviewed article.” They ask for objective evidence that they can look at themselves to verify claims. In the same way, a book is an objective source and certainly more objective than personal experience.
And given a god’s assumed omnipresence and omnipotence, direct interaction with everyone is possible.
I question this assumption of omnipotence. How do you know God is omnipotent?
Starting from your initial assumptions, the optimal method for acquiring knowledge of a god would be to have that god impart it directly to whosoever required it.
If God spoke to me, yes, I’d agree. But for those that God does not speak directly to, that option would not be available.